BoneIrregular bone

Lumbar vertebra L4

Latin: Vertebra lumbalis IV

Location: Lower back — lumbar spine

View the lumbar vertebra l4 in 3D

Function

Its nerve root powers ankle dorsiflexion (tibialis anterior) and carries the knee-jerk afferents. The L4–5 disc is the most frequently herniated in the spine.

Landmarks

  • Body
  • Iliolumbar ligament attachment
  • Spinal canal with cauda equina

Articulations (joints)

  • L3 above
  • L5 below
  • Ilium (variable iliolumbar ligament)

Clinical relevance

L4–5 disc herniation presses the L5 root: foot drop with big-toe numbness and a preserved ankle jerk.

Related conditions

Educational anatomy reference, not medical advice. About this content.